4(] BIVALVES. SPONDYLUS. 



of the Spondylus is, that its valves, which resemble those 

 of the common oyster, viz. one convex, the other rather 

 flat, have their outsides covered with longitudinal rows of 

 erect spines or ramifications. The spines are usually tu- 

 bular, ending in a point; the ramifications or branchings, 

 on the contrary, are flat, jagged, and patulous at their 

 extreme terminations. 



The spined Spondyli, as the S. Gaedaropus, &c. are 

 mostly of one color, as orange-red, purple, white, brown, 

 or yellow ; which colors, in fine specimens, are exceed- 

 ingly brilliant. 



Those which have branches or plaits, (as the S. plicatus, 

 &c.) have, on the contrary, a ground color of either of the 

 above mentioned tints, and the ramifications are left en- 

 tirely white. 



In some instances there is a compound of coloring, as 

 white and brown, purple and white, &c. which gives the 

 shell a pied or brindled appearance; and in others (es- 

 pecially those which have a tendency to being foliated as 

 well as branched) the upper valve is of one color, as pur- 

 ple or brown, while the lower valve is perfectly white. 



The valves of the Spondyli are generally unequal, the 

 lower one protruding much beyond the other, and often 

 terminating in a curved and lengthened beak. 



The hinge is furnished with two recurved teeth, which 

 are very strong and articulate, and separated by a small 

 but deep hollow; the inner margin is mostly crenulate; 

 and highly colored with orange or purple. Some of this 

 genus, like the escallops, are surmounted with ears on 

 each side of the beaks; others, on the contrary, are perfect- 

 ly earless. 



They are generally found adhering to rocks, corals, 

 &c. in groups more or less numerous, often forming large 



